a woman jogs for 2km at 8km/h and then walks for 2km at 6km/h. What is her average speed for the entire trip?

2 answers

speed = distance/time, so

(2+2)/(2/8 + 2/6) = 48/7 km/h
time at first speed = 2/8 hrs
= 1/4 hrs
time at 2nd speed = 2/6 hrs

total distance = 4 km
total time = 1/4 + 1/3 = 7/12 hrs

avg speed = 4/(7/12) km/h
= 48/7 km/h or appr 6.86 km/h